Pharynx, Cervical Trachea & Cervical Esophagus

Question 1

Dissection: Internal Features of Pharynx [19-minute video]

Answer 1

🔪

Question 2

Dissection: External Features of Pharynx [17-minute video]

Answer 2

🔪

Question 3

Dissection: Constrictors of the Pharynx and the structures passing between them [5-minute video]

Answer 3

🔪

Question 4

State the extents of the pharynx.

Answer 4

From the base of the skull to the inferior border of the cricoid cartilage at approximately the level of C6 vertebra.
[Diagram]

Question 5

State the posterior, anterior, and lateral boundaries and relations of the pharynx.

Answer 5

Posterior: Prevertebral fascia in front of cervical spine. The pharynx is separated from prevertebral fascia only by a layer of loose areolar tissue, which allows the pharynx to slide freely on this fascia during swallowing.
Anterior: Opens into nasal cavities, mouth and larynx.
Lateral: Neurovascular bundle of neck and styloid process with its attached muscles and ligaments.

Question 6

List the three parts of the pharynx, from above downwards.

Answer 6

1. Nasopharynx, lying behind the nose
2. Oropharynx, lying behind the oral cavity
3. Laryngopharynx, lying behind the larynx
4. [Diagram]

Question 7

The nasopharynx (also called post nasal space) lies behind the nasal cavities and above the soft palate. State the boundaries of the nasopharynx.

Answer 7

Roof: It is formed by: [Diagram]
(a) Body of sphenoid
(b) Basilar part of the occipital bone

Floor: It is formed by:
(a) Soft palate (sloping upper surface)
(b) Pharyngeal isthmus, an opening in the floor between the free edges of soft palate and posterior pharyngeal wall

Anterior wall: It is formed by posterior nasal apertures (choanae) separated by the posterior edge of nasal septum.

Posterior wall: It forms continuous sloping surface with roof. It is supported by anterior arch of C1 vertebra.

Lateral wall: Pharyngeal opening of the auditory tube, medial pterygoid plate of sphenoid

[Diagram 1] [Diagram 2]

Question 8

There are 3 features seen in the nasopharynx. Name them.

Answer 8

(a) Nasopharyngeal (pharyngeal) tonsil
(b) Orifice of the pharyngotympanic/auditory/Eustachian tube
(c) Pharyngeal recess: It is a deep depression behind the tubal elevation; it is called the pharyngeal recess (fossa of Rosenmüller). [Graveyard of nasopharynx]
[Diagram]

Question 9

The pharyngeal tonsil is a collection of lymphoid tissue beneath the mucous membrane at the junction of the roof and posterior wall of the nasopharynx. Briefly discuss the nasopharyngeal bursa (pouch of Luschka), and the remains of the Rathke’s pouch.

Answer 9

✓ Nasopharyngeal bursa/pouch of Luschka: a mucous diverticulum extending upwards into the substance of pharyngeal tonsil from its apex. It is provided with mucous glands.
✓ Sometimes a small dimple is seen in the mucous membrane above the pharyngeal tonsil. It represents the remains of Rathke’s pouch. A craniopharyngioma may arise from it.

[Diagram]: The 4 tonsils i.e. pharyngeal, tubal, lingual, palatine
[Diagram]: Nasopharynx showing positions of these features

Question 10

The upper and posterior margins of the opening of auditory tube are bounded by a tubal elevation known as torus tubarius, which is produced by the collection of lymphoid tissue called tubal tonsil. Two mucous folds extend from the tubal elevation. State these folds.

Answer 10

(i) Salpingopharyngeal fold extends vertically downwards and fades on the side wall of the pharynx. It contains salpingopharyngeus muscle.
(ii) Salpingopalatine fold extends downwards and forwards to the soft palate. It contains the levator palati muscle.
[Diagram: Tubal Tonsils]
[Image: Tubal Tonsils]

Question 11

State the clinical features of children affected with adenoids (enlargement of the pharyngeal tonsils).

Answer 11

✓ Nasal obstruction
✓ Nasal discharge
✓ Mouth breathing with protrusion of tongue
✓ Toneless voice (due to absence of nasal tone)
✓ Epistaxis (i.e., nose-bleeding).

(Adenoid facis)

[Image: Adenoid hypertrophy] [Diagram]

Question 12

State the boundaries of the oropharynx. [It extends from the lower surface of the soft palate above to the upper border of epiglottis below.]

Answer 12

Roof: It is formed by:
(a) Soft palate (under surface).
(b) Pharyngeal isthmus through which it communicates with the nasopharynx.
Floor: It is formed by:
(a) Posterior 1/3rd of the tongue.
(b) Interval between the tongue and epiglottis.
Anterior wall: It is incomplete and formed by:
(a) Oropharyngeal isthmus (through which it opens into the oral cavity).
(b) Pharyngeal part of the tongue.
Posterior wall: It is formed by body of C2 vertebra and upper part of the body of C3 vertebra.
Lateral wall: On each side, it is supported by pterygomandibular raphe, mandible, tongue, and hyoid bone.
The oropharynx provides common path for the food and air.

Question 13

State the features present in the anterior wall of the oropharynx.

Answer 13

(i) Lingual tonsil, formed by numerous nodules of lymphoid tissue underneath the mucous lining of the pharyngeal part of the dorsum of the tongue.
(ii) Upper free end of epiglottis, behind the tongue.
(iii) Median and lateral glossoepiglottic folds, connecting the anterior surface and edges of the epiglottis, respectively to the tongue.
(iv) Epiglottic valleculae are shallow fossae between the median and lateral glossoepiglottic folds. (Called graveyard of oropharynx because it’s hidden)
[Diagram]: Features of anterior wall of the oropharynx

Question 14

State the clinical correlation regarding crossing of pathways for food and air in the oropharynx.

Answer 14

Food may sometimes enter into the respiratory tract and cause choking. Similarly the air often enters the digestive tract producing gas in the stomach, which results in eructation (belching).

Question 15

The laryngopharynx lies behind the laryngeal inlet and posterior wall of the larynx. It lies behind the larynx and extends from the upper border of the epiglottis to the lower border of cricoid cartilage anteriorly and lower border of C6 vertebra posteriorly. State the boundaries of the laryngopharynx.

Answer 15

Anterior wall: It is formed by:
(a) Laryngeal inlet
(b) Posterior surface of the larynx
Posterior wall: It is supported by the bodies of C3, C4, C5, and C6 vertebrae.
Lateral wall: It is supported by thyroid cartilage and thyrohyoid membrane.
[Diagram]

Question 16

State the features seen in the laryngopharynx.

Answer 16

(a) Anterior wall presents laryngeal inlet and below the inlet it is supported by cricoid and arytenoid cartilages.
(b) Lateral wall presents piriform fossa one on each side of laryngeal inlet.

Question 17

The piriform fossa is a deep recess broad above and narrow below in the anterior part of lateral wall of the laryngopharynx, on each side of the laryngeal inlet. State its boundaries.

Answer 17

Medial: Aryepiglottic fold and quadrangular membrane of larynx.
Lateral: Mucous membrane covering the medial surface of the lamina of thyroid cartilage and thyrohyoid membrane.
Above: Piriform fossa is separated from epiglottic vallecula by lateral glossoepiglottic fold.
[Diagram 1] Diagram 2]
✓ The internal laryngeal nerve and superior laryngeal vessels pierce the thyrohyoid membrane and traverse underneath the mucous membrane of the floor of the fossa to reach the medial wall. [Diagram showing this]
✓ The piriform fossae form channels that direct solids and liquids from the oral cavity around the raised laryngeal inlet and into the oesophagus.

Fun fact:
The piriform fossa is sometimes artificially deepened by smugglers using lead balls to hide precious materials such as diamonds. For this reason, the piriform fossa is also called smuggler’s fossa.

Question 18

State the clinical relevance of the piriform fossae.

Answer 18

• The piriform fossae are dangerous sites for perforation by an endoscope as the internal laryngeal nerve may be damaged.
• A malignant tumor of the laryngopharynx (hypopharynx) may grow in the space provided by the piriform fossa without producing symptoms until the patient presents with metastatic lymphadenopathy.
• Ingested foreign bodies (for example, fish bones, safety pins) are sometimes lodged into the piriform fossa. If care is not taken, the removal of foreign bodies may damage the internal laryngeal nerve leading to anesthesia in the supraglottic part of the larynx and subsequent loss of protective cough reflex.

Question 19

The pharyngeal wall consists of four layers. List these layers from within outwards.

Answer 19

(a) Mucous membrane/mucous coat
(b) Pharyngobasilar fascia (pharyngeal aponeurosis)
(c) Muscular coat (pharyngeal muscles)
(d) Buccopharyngeal fascia (loose areolar sheath)

Further notes:
The pharyngobasilar fascia is the part of the middle layer of deep cervical fascia that attaches the pharynx to the skull base. It originates between the mucosal and muscular layers of the pharynx and is the primary component of the pharyngeal wall above the level of the superior pharyngeal constrictor muscle.

Question 20

The mucous membrane contains a considerable amount of elastic tissue. What type of epithelium lines the mucous membrane?

Answer 20

It is lined by non-keratinized stratified squamous epithelium except in the region of the nasopharynx, where it is lined by pseudostratified ciliated columnar epithelium (respiratory epithelium).

Question 21

Discuss the pharyngobasilar fascia.

Answer 21

It is a fibrous thickening of the submucosa. It lines the muscular coat and is thick near the base of the skull but thin and indistinct inferiorly. The pharyngobasilar fascia is thickest:
(a) in the upper part where it fills the gap between the upper border of superior constrictor and the base of the skull, and
(b) posteriorly where it forms the pharyngeal raphe.

Question 22

The muscular coat consists of two layers of striated muscles; an outer layer and an inner layer. State what is found in those layers.

Answer 22

Outer layer: 3 pairs of circular muscles called constrictors.
Inner layer: 3 pairs of longitudinal muscles.

Question 23

What is worth noting about the buccopharyngeal fascia?

Answer 23

It is an inconspicuous fascia, which covers the outer surface of constrictor muscles. In the upper part, it is also prolonged forwards to cover the buccinator muscles, hence the name buccopharyngeal fascia. Above the upper border of the superior constrictor, it blends with the pharyngobasilar fascia.

Question 24

The aggregations of lymphoid tissue underneath the epithelial lining of pharyngeal wall called tonsils, surround the commencement of air and food passages. These aggregations together constitute an interrupted circle called Waldeyer’s ring. State the components of the Waldeyer’s ring.

Answer 24

1. Pharyngeal tonsil (nasopharyngeal tonsil), postero-superiorly
2. Lingual tonsil, anteriorly
3. Tubal and palatine tonsils, laterally
4. [4-minute video]: Waldeyer’s ring, [Diagram]

Question 25

State the function of Waldeyer’s ring.

Answer 25

It is thought that Waldeyer’s ring prevents the invasion of microorganisms from entering the air and food passages and this helps in the defense mechanism of the respiratory and alimentary systems.

Question 26

Constrictor muscles of the pharynx. They all constrict the pharynx, thus helping in deglutition. Their posterior attachments are at the pharyngeal raphe except cricopharyngeus part, which is continuous with its counterpart and thus is like a sphincter. State the anterior attachments of:
(a) superior constrictor (quadrilateral in shape)
(b) middle constrictor (fan shaped)

Answer 26

(a) pterygomandibular raphe and adjacent bone on the mandible and pterygoid hamulus. [Diagram]
(b) upper margin of greater horn of hyoid bone and adjacent margins of lesser horn and stylohyoid ligament [Diagram]

Question 27

State the anterior attachments of the:
(a) thyropharyngeus part of inferior constrictor
(b) cricopharyngeus part of inferior constrictor

Answer 27

(a) Oblique line on lamina of the thyroid cartilage
(b) Cricoid cartilage
[7-minute video]: the pharyngeal muscles

Question 28

Briefly discuss Zenker’s diverticulum/pharyngeal pouch.

Answer 28

✓ The potential gap posteriorly between the thyropharyngeus and cricopharyngeus is called pharyngeal dimple or Killian’s dehiscence.
✓ The mucosa and submucosa of the pharynx may bulge through this weak area to form a pharyngeal pouch or diverticulum.
✓ The formation of pharyngeal pouch in the region of Killian’s dehiscence is attributed to the neuromuscular incoordination in this region, which may be because the two parts of the inferior constrictor have different nerve supply. The propulsive thyropharyngeus is supplied by the pharyngeal plexus and the sphincteric cricopharyngeus is supplied by the recurrent laryngeal nerve. If the cricopharyngeus fails to relax when the thyropharyngeus contracts, the bolus of food is pushed backwards and tends to produce a diverticulum.

Question 29

State the innervation to:
(a) superior constrictor, middle constrictor, and thyropharyngeus part of inferior constrictor. (hint: these are from 4th pharyngeal arch)
(b) cricopharyngeus part of inferior constrictor. (hint: this is from 6th pharyngeal arch)

Answer 29

(a) superior laryngeal nerve of X
(b) recurrent laryngeal nerve of X
[7-minute video]: the pharyngeal muscles

Question 30

Click on Answer to check out a diagram and short explanations on Passavant’s ridge.

Answer 30

[Diagram]

Question 31

There are gaps that exist in the pharyngeal wall in relation to constrictor muscles. State the structures passing through these following gaps:
(a) Between the base of skull and the upper concave border of superior constrictor [sinus of Morgagni]
(b) Between the superior and middle constrictors
(c) Between the middle and inferior constrictors
(d) Between the lower border of inferior constrictor and the esophagus [in the tracheo- esophageal groove]

Answer 31

(a) Between the base of the skull and the upper concave border of the superior constrictor
✓ Auditory tube
✓ Levator palati muscle
✓ Ascending palatine artery
✓ Palatine branch of the ascending pharyngeal artery
(b) Between the superior and middle constrictors
✓ Stylopharyngeus muscle
✓ Glossopharyngeal nerve
(c) Between the middle and inferior constrictors
✓ Internal laryngeal nerve
✓ Superior laryngeal vessels
[These are the structures that pass through the foramen in the thyrohyoid membrane.]
(d) Between the lower border of inferior constrictor and the esophagus
✓ Recurrent laryngeal nerve [inferior laryngeal nerve]
✓ Inferior laryngeal vessels

Question 32

(a) State the location of the pharyngeal plexus of nerves.
(b) Name the nerves that form the pharyngeal plexus.

Answer 32

(a) It lies on the posterolateral aspect of the pharynx over the middle constrictor underneath the buccopharyngeal fascia.

(b) It is formed by:
1. Pharyngeal branch of the vagus nerve carrying fibres from cranial part of the accessory nerve
2. Pharyngeal branch of the glossopharyngeal nerve
3. Pharyngeal branch from superior cervical sympathetic ganglion
4. [7-minute video: Pharyngeal plexus]

Question 33

Name the arteries that supply the pharynx.

Answer 33

The branches of the following arteries supply the pharynx:
1. Ascending pharyngeal artery (from external carotid artery)
2. Ascending palatine and tonsillar artery (from facial artery)
3. Greater palatine and pharyngeal artery (from maxillary artery)
4. Lingual artery (from external carotid artery)

Question 34

Lymph from the pharynx drains into which nodes?

Answer 34

(a) upper deep cervical lymph nodes
(b) lower deep cervical lymph nodes
(c) retropharyngeal lymph nodes

Question 35

State the boundaries of the tonsillar fossa.
[Hint: anterior, posterior, apex, base, lateral wall]

Answer 35

Anterior: palatoglossal arch containing palatoglossus muscle
Posterior: palatopharyngeal arch containing palatopharyngeus muscle
Apex: soft palate where both arches meet
Base: dorsal surface of the posterior one third of the tongue
Lateral wall (tonsillar bed): superior constrictor
[Diagram]

Question 36

Name five arteries that supply the palatine tonsil.

Answer 36

1. Tonsillar branch of facial artery (it is the principal artery and enters the lower pole of the tonsil by piercing the superior constrictor)
2. Dorsalis linguae artery
3. Ascending palatine artery
4. Ascending pharyngeal artery
5. Greater palatine (descending palatine) artery

Question 37

State the venous drainage of the tonsil.

Answer 37

Smaller veins from the tonsil drain into the paratonsillar vein. The paratonsillar vein descends from the soft palate across the lateral aspect of the tonsillar capsule and pierces the superior constrictor to drain into the pharyngeal venous plexus.

Question 38

State the nerve supply of the palatine tonsil.

Answer 38

Glossopharyngeal nerve
Lesser palatine branches of the sphenopalatine ganglion

Question 39

The trachea is a non-collapsible membrano-cartilaginous tube forming the beginning of lower respiratory passage. State its extents.

Answer 39

From the lower border of cricoid cartilage at the lower border of the C6 vertebra to the lower border of T4 vertebra in supine position, where it terminates by dividing into right and left principal bronchi.

Question 40

The cervical part of trachea extends from the lower border of cricoid cartilage to the upper border of manubrium sterni. State its relations.

Answer 40

[This is best studied with an atlas. Don’t spend time trying to memorize all this.]

Anteriorly, from superficial to deep it is related to:
(a) skin,
(b) superficial fascia containing anterior jugular veins and jugular venous arch (crossing in the suprasternal space of Burns),
(c) investing layer of deep cervical fascia,
(d) sternothyroid and sternohyoid muscles,
(e) isthmus of thyroid gland in front of the 2nd, 3rd, and 4th tracheal rings,
(f) inferior thyroid veins and arteria thyroidea ima (occasional),
(g) left brachiocephalic vein in children may rise in the neck,
(h) thymus gland (in children), and
(i) brachiocephalic artery (sometimes) in children.

Posteriorly it is related to:
(a) esophagus,and
(b) recurrent laryngeal nerve in the tracheoesophageal groove (on each side).

On each side it is related to:
(a) lobe of thyroid gland extending up to the 5th or 6th tracheal ring, and
(b) common carotid artery in the carotid sheath.

Question 41

State the blood supply and lymphatic drainage to the cervical trachea.

Answer 41

Arterial supply: branches of inferior thyroid artery
Venous drainage: into left brachiocephalic vein
Lymphatic drainage: into pretracheal and paratracheal nodes [Diagram]

Question 42

State the nerve supply to the cervical trachea.

Answer 42

Parasympathetic fibers: recurrent laryngeal nerve of X.
Secretomotor and sensory to the mucus membrane and motor to the trachealis muscle.
Sympathetic fibers: from middle cervical sympathetic ganglion; vasomotor in nature.

Question 43

The esophagus is 25 cm long muscular tube, which connects pharynx with the stomach. State the extents of the cervical esophagus.

Answer 43

It extends from the lower border of cricoid cartilage to the superior border of manubrium sterni. It begins in the midline but inclines slightly to the left as it descends.

Question 44

State the relations of the cervical esophagus.

Answer 44

[This is best studied with an atlas. Don’t spend time trying to memorize all this.]
This diagram provides a good summary: [Diagram].
Anteriorly, it is related to:
(a) trachea and
(b) recurrent laryngeal nerve.

Posteriorly, it is related to:
(a) prevertebral fascia,
(b) longus colli muscles, and
(c) vertebral column.

On each side, it is related to:
(a) lobe of the thyroid gland,
(b) common carotid artery, and
(c) thoracic duct on the left side.

Further note:
The prevertebral layer of deep cervical fascia forms a movable base on which the trachea and esophagus move up and down during swallowing and phonation.

Question 45

State the blood supply and lymphatic drainage of the cervical esophagus.

Answer 45

Arterial supply: inferior thyroid arteries.
Venous drainage: inferior thyroid veins and left brachiocephalic vein.
Lymphatic drainage: pretracheal and deep cervical lymph nodes.

Question 46

State the clinical correlation of the esophagus.

Answer 46

• The left margin of the esophagus projects laterally from behind the trachea in the region of the neck. Therefore the cervical part of esophagus can be mobilized and exposed surgically more easily from the left side.
• The interior of the esophagus can be examined in vivo by esophagoscope. This procedure helps to obtain tissue biopsy or removal of swallowed foreign body.